1. Field of the Invention
This invention relates to bearings, and more particularly to bearings which have lubricated bearing surfaces.
2. Description of the Prior Art
A number of conventional bearing assemblies are known which operate with the use of lubricants to prolong the life of the bearing and the apparatus in which the bearings are used, as well as to increase the efficiency of the bearing. Vibrations are encountered as a result of the loads and other forces which are imparted to the bearings and contacting surfaces. Administering lubricants to a bearing surface is challenging because in many instances the bearing surfaces which require the lubrication are in contact with another surface.
U.S. Pat. No. 4,568,204, which issued on Feb. 4, 1986 to William S. Chambers and is assigned to Kingsbury, Inc., the assignee of the current invention, and which is incorporated herein by reference, discloses a journal bearing with a leading edge oil distribution groove. The oil distribution grove directs the oil against the working faces of the shoes where it is needed. The journal bearing of the ""204 patent provides an improved bearing which conserves oil.
In the operation of bearings, there are generally different ways to run the bearings. For example, a bearing can be run flooded, whereby a sufficient quantity of oil is delivered to the bearing to provide as much oil as the bearing needs. However, in some cases, although flooding the bearing with an endless supply of oil may minimize vibrations, it is not efficient. In many bearing applications, it is preferred to run bearings evacuated, and not flooded. This is generally done to conserve power and to enable the bearing to run cooler.
While certain bearing vibrations may be considered to be minimal, it is often important to reduce even these vibrations as much as possible. To this effect, some specifications for machinery require that certain tolerances be met, such as, for example, a maximum vibration level. Vibration levels are often additive and take into account the total cumulation of vibration. Any subsynchronous vibration will therefore add to the total level of maximum acceptable vibration.
While periodic adjustments can be made to machinery over time in order to temper the undesirable vibrations, it is for the most part time consuming to make the adjustments. Moreover, if the vibrations are allowed to remain before an adjustment is made, the bearing instability caused by the vibrations can eventually ruin a machine, as the bearing surfaces as well as other components may wear excessively against each other.
It is known practice to admit lubricant through a hole or passageway to lubricate the surface of a bearing. Where oil is pumped through a hole, the oil is most usually abundant in those areas of the bearing surface immediately near the hole, and least abundant in the areas furthest from the hole. U.S. Pat. No. 4,568,204 provides an improvement in a journal bearing to supply lubricant to those areas of a bearing surface which are in need by providing a distribution groove on the bearing shoe work surface and utilizing o-rings to prevent spillage of oil into areas where it is not needed.
It is desirable to reduce the oil flow in a bearing lubrication system without effecting the operation of the bearing assembly. Energy conservation is promoted by reducing the power loss, reducing the amount of oil used and increasing the load carrying capabilities. A further benefit is that when the amount of oil required is reduced, the system may employ a smaller pump and other auxiliary equipment and therefore be more efficient.
It is an object of the present invention to provide a bearing assembly which has the benefits of an evacuated bearing assembly, but with the lower initial vibration levels associated with flooded bearing systems.
The present invention provides a novel bearing apparatus and method for lubricating the bearing which increases the load carrying capacity, uses less oil, consumes less power, enables the use of smaller auxiliary equipment, and is more efficient to operate than the prior bearing types.
The objects of the invention are accomplished by providing a lubricant distribution feature which facilitates coverage of a bearing working face with a lubricant across its surface. The lubricant which is admitted to the bearing surface is redirected from one location on the bearing surface to another location on the same bearing surface. Preferably, a hole or passageway in the bearing components for the admission of the lubricant, such as oil, delivers the oil to the bearing surface. Excess oil is collected from the bearing surface and redirected to those areas of the bearing surface which are in need of oil. Preferably, the redirection of the oil is accomplished to provide an even distribution of lubricant across the bearing surface. The amount of oil therefore is conserved since, what was excess oil in one area of the bearing working face is now captured and supplied to other areas without the need to increase the oil flow rate. Channels in the bearing surface are provided on each lateral edge thereof. The channels are configured to increase the contacting surface of those areas of the bearing working face which would otherwise not received a sufficient amount of oil, unless the oil was supplied in an excessive or flooded condition.
It is another object of the present invention to accomplish the above objects where the bearing is a journal bearing having a plurality of shoes positioned around a ring, and where the lubricant is redirected over the working face of the shoes to reduce the amount of oil required.
It is another object of the present invention to provide a shoe for use with bearings, and in particular with journal type bearings, which has the novel feature of redirecting the oil from one area of the shoe working face to another area which is in need of lubricant.